This sort of thinking is also, I regret to report, increasingly widespread in social science and the influence here is even more corrosive because there is an added dimension: an avoidance of doing any actual research.

The 'there's nothing outside the text' crowd are a minority, yes, but they're a growing one; their cherished 'theory' provides a good excuse to never actually leave the campus or delve into primary research. A box set of The Wire and some theory textbooks and you're good to go. No need to go to the effort of speaking to 'real' people (what a regressive, rationalist notion!).

Of course I do not think that that textual analysis is a bad thing; rather, I am concerned that because of the narcissistic excesses of the 'textualists' the whole concept becomes ghettoised, making it extremely difficult for any fresh thinking to break through.

As a grad student or early career academic either you submit to the empiricist mainstream, which comes out in a rash at the sight of anything remotely 'continental', or shipwreck yourself on one of a handful of 'discourse friendly' institutional islands where you're not allowed to 'go outside the text' or make any positive claims about the world at all -- if it's beyond the horizon (of discourse) it doesn't exist!.

It's no wonder it all ends up going a bit 'Lord of the Flies' in these places.